1. Field of the Invention
The present invention relates to a cholesteryl compound with liquid crystalline properties, and a rewritable full-color thermosensitive recording material comprising the above-mentioned cholesteryl compound.
2. Discussion of Background
Color photographs and photocopiers are known as recording materials capable of recording a full-color image, but not capable of rewriting the recorded image. On the other hand, there are known recording materials capable of rewriting the recorded information, but not capable of achieving full-color recording, for example, a thermosensitive recording material comprising a long-chain alkyl carboxylic acid derivative such as behenic acid; an optical recording material comprising a photochromic compound such as a spiropyran derivative; and a magnetic and magneto-optical memory material.
As shown in the above-mentioned conventional recording materials, full-color recording and rewritable recording are not achieved at the same time.
Some image display materials, for example, television devices and liquid crystal devices can display full-color changeable images. However, these image display materials cannot be made compact, for instance, into a thin card that can be kept in a wallet. In addition, the color image displayed in the above-mentioned display materials cannot be stably maintained without a power source. For these reasons, the above-mentioned image display materials cannot be used as recording materials.
Achievement of rewritable full-color recording using liquid crystalline compounds is reported (N. Tamaoki et al. Advanced Materials 9 (14), 1102 (1997)). In this case, however, the peak of the reflection band of the reflection spectrum is, at most, 610 nm on the long wavelength side, so that it is difficult for the above-mentioned liquid crystalline compounds to assume a red color.